During the past five years the CNRU Immunology Core Laboratory has worked to facilitate the study of nutrition, immunity and cancer prevention by providing a comprehensive battery of immunological tests for nutrition oriented investigators of the Cooperative Core Laboratory and Clinical Nutrition Research Unit and the biomedical community: The American Health Foundation, Memorials Sloan-Kettering Cancer Center, Cornell University Weill Medical College-New York Presbyterian Hospital, The Strang Cancer Prevention Center, The Rockefeller University, and in the future the Westchester Medical Center-New York Medical College. A second major function of the Core laboratory is to serve as educators and consultants to investigators in study design, in the selection of tests and in the interpretation of data. A related third goal has been to develop new methodologies and to refine existing techniques that are potentially useful for new and evolving CNRU investigations. The focus of the Immunology Core Laboratory is to undertake studies relating immunological function to nutrient status, cancer prevention and control. The development of new immunological approaches including technology and standardization were initially crucial for this work (1-4). This has been a continuing theme during the past five years (5-8) with the evolution of more sensitive and well standardized techniques.